


His Lust

by WasInReality



Category: Ao no Exorcist | Blue Exorcist
Genre: Demons, Hanahaki Disease, Hurt/Comfort, M/M, Mentions of Rape, Rape/Non-con Elements, Romance, Underage Sex, mentions of torture
Language: English
Status: In-Progress
Published: 2020-10-20
Updated: 2020-10-21
Packaged: 2021-03-08 17:41:38
Rating: Mature
Warnings: Rape/Non-Con, Underage
Chapters: 4
Words: 6,807
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27120592
Author URL: https://archiveofourown.org/users/WasInReality/pseuds/WasInReality
Summary: At the age of seven, Rin was stolen away to Gehenna. What happens when Mephsito needs Rin to come back to Assiah to help in an exorcist case? What would his old family members think of his new title as the demon king of lust?This is a collaboration with AnimalsEML on Wattpad who is writing our wonderful smut scenes, I'm terrible at them.
Relationships: Amaimon/Okumura Rin, Okumura Rin/Mephisto Pheles
Comments: 1
Kudos: 52





	1. Prologue

Twins are 7

“Alright Rin, stay here and don’t move,” Shiro told his oldest son. Rin had a bad habit of wandering off when he got bored, especially when he was left alone with no-one to stop him from getting into troublesome situations.

Shiro and Yukio entered the males’ bathroom in the store, leaving Rin on his own. They had got some extra supplies for the week and tonight’s dinner. Shiro planned on helping Rin learning to cook and needed some more ingredients.

Though at the end Yukio needed a “number one” and thus leading to Rin being let on his own. The only problem is, that was five minutes ago and Rin was bored.

He walked out of the store to find something to entertain him. He knew he was going against his father’s words but he was bored!

He looked up at the fresh blue sky dotted with a few what looked to be fluffy clouds. The sun shone bright but a light breeze was present. It was the beginning of the four cold months, September. 

Rin sat on a bench just outside the supermarket and looked up at the sky and frowned thinking about what his father told him.

As the navy-haired boy was distracted by his thoughts he was brought out of them when he was grabbed at an incredible speed and landed on the roof. 

His wide eyes looked up at the white-haired teenage boy and gasped before looking back down. “Woah! Cool! How did you do that mister?!!” Rin shouted out so amazed and curious as any child would be.

“I’m a demon you see, young prince.” He responded formally as if he was talking to royalty.

Rin gasped only now noticing the prominent ram horns on his head and tail swishing behind him.

“Prince?”

“Of course, you are the Prince of Gehenna, my younger brother, and heir to the throne of Gehenna.”

“Ga-he-na?” The younger boy asked, struggling to pronounce the foreign word.

“Yes, it’s a wonderful place, I’m sure you’ll love it.”

“What’s it like?” Rin asked, tilting his head in curiosity.

“Why don’t you come see for yourself?” Rin only now noticed the long black claws the boy had to go with his demonic look as he offered his large hand.

Rin was about to take his hand with a smile when it dropped - which didn’t go unnoticed by the demon. 

“What is it little one?” Astaroth asked, hoping it wasn’t anything that would cause his plan to fail, he didn’t want to have to take the boy by force.

“What about Yukio and daddy?”

Astaroth replied with a vague response, “you’ll see them again.” Rin reluctantly nodded before giving the teen a small smile.

“Well then, we better be off.”

Rin smiled as he held the man’s hand walking off to the gate.

“Ew! What is that?”

“That is the Gehenna Gate.” The man responded. “Now relax your body and just let yourself sink into it, I’ll be right here with you young prince.”

Rin hummed as he poked at the bubbling gate with eyes and faces around the rim. Eventually, Rin did as he was told and left Assiah for years to come.

* * *

“Daddy, I can’t find Nii~san…” Yukio told his father worriedly as he constantly looked around for the navy-haired boy while holding his father’s bigger hand.

Shiro made a ‘tsk’ sound and whispered under his breath, “Rin was supposed to stay here.” He had a worse feeling about Rin being missing than he had any other time the boy had wandered off.

The two searched for hours which turned into the whole church looking for him. The hours turned into days, the days into weeks, weeks into months, and eventually years. Even if was just them being on the lookout for a boy with navy blue hair, blue eyes, and whatever other body changes he had gotten over the years.


	2. Back to Assiah

**Summary for the Chapter:**

> Exploring memories of Rin first in Gehenna and Mephisto has decided to visit our young demon king.

(Third person view) 

When Rin was first brought to Gehenna he detested it, he wanted to go home. Whenever Rin told Satan wasn't his father he would be locked in his room. However, when the Kouma sword broke he was tortured for spewing such lies to his father or disobeying. Seeing as Satan was the one who did the torturing it left scars due to his power, not even his demonic could heal the wounds his father gave him. The mental scars were the worst though his own screams in his nightmares haunt the boy. Satan would drag his claws along his body, bite into his skin, break his bones one by one only for them to heal minutes later and repeat the process. Chunks of skin would be taken out of him and would be forced to watch Satan eat his flesh. But the thing that terrified Rin the most was that maybe one day he would be just like his father. As Rin got older he started to understand that if he didn't want to get tortured he just had to obey. 

Satan always put Rin through immense training even before the Kouma sword broke. To Rin it was tiring and like he was being broken every day over and over but to Satan, he was turning his son into the perfect demon, a role model for all. Satan blocked out the knowledge that the boy was still half human - less than what he was in Assiah - eventually, he was trained enough to be a demon king and at the age of 15 he became the demon king of lust. 

No exorcists new of the new demon king other than higher-ups until they had figured out what they were the king of. 

There are only considered seven demon kings - eight if you include Rin - as Lucifer was locked up for eternity for conspiring against Satan. The demon kings were always kind to Rin and always tried to cheer up the young half-demon when he was down after what Satan had done. Samuel never helped though as he was always in Assiah but Rin always loved spending time with him when he visited Gehenna. He wasn't, teasing, mocking like all the demon Kings said he would be, he acted exactly like a brother should, kind, caring and loving he would tease and joke playfully every now and though. 

Astaroth wasn't very nice but Rin couldn't bring himself to blame. Him though. He didn't have a good childhood - well, not like any of them did but not as good as the rest of the demon kings - because he was the exact opposite of Satan, king of rot. Rot was weak to fire therefore making Astaroth weak in Satan's eyes. 

Amaimon was also fun, he was the one that helped Rin figure out what he was the demon King of. 

Flashback 

Rin is 14 (14 in A Assiah - 700+ in Gehenna)

Rin had just arrived at Amaimon's Castle and luckily the earth king was there. Rin refused to bother the rest of his busy brothers and Amaimon being the only free one. Amaimon would always try to cheer the young half-demon up but never really helped but always thanked him for trying and what he did always put a smile on his face afterwards. 

"Amaimon!" Rin screamed tears running down his face as ran to Amaimon who only picked him up and hugged the cry half-demon. Affectionate touching invariably made him happy. 

Amaimon hugged the boy close to him as he cried into his chest. Amaimon wasn't good with situations like these but he had an idea he was waiting to try out when Rin was next upset. Amaimon had suspicions that he wished to confirm. 

(Till the end of flashback is written by AnimalsEML on Wattpad)

"I know something that will cheer you up, little brother," Amaimon spoke and the younger demon looked at him slightly confused.

And he became even more confused when the older demon pinned him down on his back on the mattress.

Rin has always been somehow afraid of his older brothers and was worried that the green-haired demon would torture him when Amaimon did a move that made Rin gasp.

Rin could feel Amaimon's sweet lips against his and without thinking any other second, he kissed back. 

Amaimon took notice of it and started to kiss Rin even more passionately, roughly. It was breathtaking to Rin who wrapped his arms around Amaimon's neck and deepened the kiss.   
But to Rin's misfortune that second, Amaimon pulled away and placed butterfly kisses on the younger demons jaw down to his neck to find the sweet spot of Rin's. And bingo!

Rin moaned out loudly, tugging at Amaimon's hair which caused the green-haired male to groan in both lust and slight pain.   
He soon pulled away and tore up Rin's white shirt, exposing his chest before leaning in closer to Rin's ear.

"I will make you feel so great, Rin~~." Amaimon whispered in a husky tone and the younger demon shivered at his words.  
Rin has always felt like there was something that could make him happy, satisfied. But he never knew what the thing was.   
Until now...

The older demon pressed his lips against Rin's, kissing him passionately before biting his bottom lip softly for permission and Rin allowed him to deepen the kiss. Their tongues touched and Rin moaned even more as the older demon touched Rin's sides down to his waist.

Amaimon's touch was like electrifying, a feeling of feeling so great. Rin wasn't familiar with the feeling, but he was sure he would want to do it more than once.

"Amai-san~." Rin moaned out loudly without feeling any shame. 

Amaimon smirked, pulling away from the kiss and he sat up, straddling the younger demons waist.

The sight of the older demon taking off his shirt and blazer made Rin nearly drool, Amaimon becoming satisfied with Rin doing so.

Amaimon leaned in again, not to kiss Rin this time, but place small, sweet kisses to Rin's right nipple and he licked it, making Rin moan out loudly.

After playing some minutes with his nipples, Amaimon travelled down to the zipper on Rin's blue jeans and dragged it down with his own teeth.

Rin felt his boxers tighten, not really knowing why it was paining him, making him suffer in slight pain.

Soon enough both his jeans and boxers were off, Rin moaning at the feeling of his manhood being finally free. He closed his eyes but didn't get to have his eyes closed a long time when he gasped at the new feeling.

The younger demon male looked down to see Amaimon licking the base of his manhood, up to the tip and a moan escaped from Rin's throat.

The older demon took Rin's whole length in his mouth, sucking and bobbing his head up and down, earning louder and louder moans from the young demon.

Rin has never felt this great, satisfied, but he wanted so much more of the green-haired male's touch.

Something burned into him, such a strong lust, desire...

"A-AMAIMON!!?" Rin's eyes snapped when he felt something burst and the white hot seed filled Amaimon's mouth. He swallowed it hungrily, licking his lips before standing up and towering over him.

"You taste so nice, little brother~" Amaimon whispered huskily and Rin placed a kiss on his lips before turning them around so Amaimon would be the bottom. 

Amaimon smirked and let Rin kiss him as they kissed passionately, but soon Rin grew tired. His lust becoming only stronger and stronger. 

Amaimon somehow noticed it and pinned the younger demon down on his back on the bed and took off his pants. Rin saw the green-haired demons manhood, drooling at the sight.

The lust became even stronger and Rin sat up to give Amaimon the same treatment like Amaimon gave Rin.

The green-haired male took notice of it and smirked, immediately pinning Rin down on the bed again.

"No no. I want it too~." Amaimon whispered huskily into Rin's ear. "And we have many times we can do this. But now, all pleasure is yours~."

He placed a kiss on Rin's lips, placing the tip of his manhood at Rin's hole.

"The pain will sudden away~." the green-haired male whispered and then pushed his whole length into Rin.

The younger demon cried out in pain, it felt worse than anything his father has done to him. But, Amaimon kissed away the tears, whispering sweet words to Rin as he gave time to adjust.

The younger demon nodded slightly, wrapping his around Amaimon's neck and Amaimon took the hint and started to move inside Rin at a slow pace.

After a few minutes, if even that, Rin begged the green-haired demon to go faster wich Amaimon did with pleasure.

"Amaimon-sama!" Rin moaned and the older demon smirked. 

"-sama? I love how you moan it after my name, little brother~." He spoke, thrusting into Rin and hitting the very special spot which caused the younger demon to literally scream out Amaimon's name.

"Please! Right there! Harder!" Rin pleaded and Amaimon did it with pleasure, hitting the spot all over again.

The younger demon was nearly clinging onto the older, wrapping his legs around Amaimon's waist and burying his nails into his shoulders making Amaimon groan in slight pain.

Something started to build up in Rin's stomach, something was tensing up inside him as Amaimon only went faster, harder and deeper into Rin.

"R-Rin... I'm about to cum." his voice trembled.

"Yeah. M-me too." Rin cried out. The knot in his stomach about to burst...

And so it did. 

The two demons cried out each other's names, Rin feeling more great, satisfied than ever.

He now knew what would make him happy, feel satisfied.

Once the green-haired demon pulled out, he lay down next beside Rin, pulling in Rin closer to his chest.

"Do you feel better, little brother?" Amaimon asked the younger demon who nodded slightly, feeling exhausted.

"Yes..." he mumbled and Amaimon smiled softly.

"I'm glad to hear it... Rin." 

Soon Rin drifted to sleep, not knowing he would become the demon kin of lust, desire, and sex...

Flashback over

After the incident, whenever Rin was upset Rin would go to Amaimon for sex sometimes to the others as well, they all had ideas of what I could be the king of some already has the idea of lust. 

Amaimon also had to tell Satan about his discovery as it was law, you were never to hide anything from Satan if you did you would be in deep trouble. Satan had got an idea from the new information that Rin did not like at all. Rin never felt dirty or ashamed after sex but with Satan he did. Satan would rape the boy for the fun of it not taking notice to the boy's discomfort or if he did he didn't care. 

When Rin became a demon king he got his own terf which was created by Satan. He had his own castle and several other things in it. It looked more like a love ground than anything and had homes in large blossom trees in which demons would breed, mostly rin's kin. Lakes and fields what would fill the area along with the blossom trees. Rin and his kin never really took notice to the beautiful scenery but rather ignored it as all the wanted were their sexual desires to be fulfilled as they were succubi (plural for succubus) after all

Rin's kin was exceptionally strong for his rank in the anarchy. They also had many abilities, being able to take on a human form by possessing and being able to change such body to an extent. Their main power was desire, whatever their heart desired they could do, commit a crime, eat, sex, you name it. Crimes had risen largely since Rin came into the picture.

* * *

Present: Rin is 16 (907)

It's been just over nine hundred years since Rin was taken from. Assiah to Gehenna. However, it's only been nine years in Assiah time. A year in Assiah is a hundred years in Gehenna. 

Rin had just got back to his castle after running away from Satan's guards with Iblis after burning down most of the west end of the dark forest. Iblis was always a daring woman making his times with the women fun but they both need to braise themselves for a scolding from Egyn soon. Iblis and Egyn were complete opposites which made sense considering their power but it was funny whenever they were in the same room.

Rin was brought out of his thoughts when one of his servants came in kneeling in front of her king. The demon had small horns and small bat wings on her back, she wore revealing clothes showing off her pinkish skin almost tinted red. Her eyes were blue with black hearts in the middle as her pupils with a red slit in the middle, the hearts would disappear if she were to activate her power to an extent. 

"Sir," Rin sat up straight after slumping on the couch. "Go on," he commanded as he motioned for the succubus to stand up. They looked into each other's eyes as it was only respectable in the realm of demons especially to a royal. "King Samual has returned from. Assiah and wishes to speak with you immediately." What!" It wasn't a question only response in his shock before he composed himself again and shooed her away. Rin had thought the time and space king would at least give him a warning. He was only worried due to the fact he'd only met the man a handful of times throughout the centuries and his appearance was dishevelled after 'playing' with Iblis.

"Calm down little brother, your clothes do not affect me, " 'but it would be nice to see you in something a little less... Dirty.' He said the last part in his thoughts. Rin was broken out of his thoughts once again shocked. "S-Samuel,' Rin stuttered. Samuel smiled and opened his arms. "Come here," Rin pounced on him like a cat as Samuel stumbled back from the force of the hug, he placed his chin on top of the smaller's head and Rin's face lay on the man's chest taking in his scent and smiled at the known scent he missed dearly - it was ravishing. 

After a few minutes, they let go and Samuel looked down at the smaller who knew why he was so short and had to tell him centuries ago as Satan would not as well as telling him of Satan and was never caught due to being in Assiah before he could be punished. Samuel probably has millenniums of torture to go through. 

"so, why are you here?" Rin asked bewildered by why the older man was here. "Well, little brother!" He announced pointing his index finger in the air with a devilish grin plastered on his face per usual. "You see I need help with an Exorcist case-" before Samuel could finish his explanation he was interrupted. "How am I going to get out of Gehenna." Rin sat back down crossing his arms and legs. "Sneak you out." His once again cunning voice, prominent along with his trademark smirk. "Can I see them?" Samuel knew exactly what he meant and the sadness distinguished sadness in the youngers voice, only making it that more obvious. "Of course little brother," Samuel replied. "That's all you need to say." Rin got up to shower and change out his mucky clothes, "alright meet me out front." Samuel poofed himself away in a cloud of pink smoke.

* * *

Rin came out with ack skinny leather jeans make his curves and ass look prominent or 'sexier' in Rin's words he also just liked the jeans in general. It also gave people and demons more reason to fulfil his sexual desires if he was more attractive - more than he ready was. He also had a black t-shirt that said 'First of all yes, second of all yes' and a red leather jacket but buckles and belts and straps around it. He also wore his trademark high heals that ended just bow his knees and thin heels on the bottom. 

"Shall we go?" Samuel asked and received a nod from Rin in return. They made their way to the monthly Gehenna gate. There was a gate that opened randomly for a month every year so happened this month was it. Lucky them. 

However, Rin was scared, no, not of the gate, not of Assiah, not of humans but what they will think of him when they finally see him again. They hadn't seen him in nine years what would they do when they see his new personality, Rin had thought about putting an act on but discarded the possibility in case it wrecked their relationship that they once had. But the one thought that stuck out from the rest was: _'will they be happy to see me?'_


	3. Can I get my special "treatment" yet?

**Summary for the Chapter:**

> Back in Assiah and Mephisto is already keeping secrets. Two shocked mm seeing their son and brother again only for him to be taken away again for special "treatment".

Rin and Samuel had just stepped out of the Gehenna gate. Seeing the two together wasn't odd as Rin was the only other brother besides Amaimon he liked and even saying he liked Amaimon was a stretch. 

Samuel sat down in his desk chair and Rid stood beside him. "So, what's this case about anyway?" Rin queried while looking around, it was only natural he hadn't seen Samuel's office before nor had he seen Assiah in over 900 years. "I wouldn't normally tell you bu~t..." He sang out, "you are my favourite brother." Samuel looked away grumpy mumbling the last part. "Oh?~" The seductive voice Samuel knew all too well filled his ears and he turned to Rin who was now sitting on the man's lap with his arms around his neck and felt the youngers breath on his ear. "Sorry, I couldn't quite catch that," Samuel could hear the smirk in his voice as he bit his ear lobe and Samuel felt a shiver go up his spine. 

Samuel had to end this quickly or he would fall victim to the lust demons actions. "Damn you Rin," Samual cursed, it takes a lot of effort to resist Rin when he's like this even if you weren't into him and not being into him is a challenge in itself. If you played it right you could win and here was the space and time king slowly falling victim. 

"C'mon you can tell me, I won't tell anyone else." He sounded alluring yet playful. "Someone's horny," Samuel commented and Rin quickly sat up and snapped out his seductive state. Samuel had won. "Of course I am, Amaimon's wandered off somewhere leaving me sexless," Rin replied clearly irritated. Samuel smirked at the new information. "Well, how about a deal?" Rin raised an eyebrow prompting older to carry on. "You help with the case and I fulfil your sexual desires," Samuel told him and Rin thought for a moment before sighing. "Alright, fine." Rin really wasn't in the mood to help with a case right now, he hadn't had sex in a month what did anyone expect him to be like. "And to answer your first question, there is a guy hiding demons but cannot reach them without a key and pin number to the vault," Samuel informed his once sly voice changed to a much more informative one. "Let me guess you want me to get answers from him?" The navy-haired boy asked wanting the older to confirm. Samuel hummed in response as the smaller got off his lap and getting up after him telling the younger better be off.

Samuel looked back with a smirk "Mr Fujimoto and Mr Okumura will be there." He turned back and Rin was once again in deep thought.

* * *

Shiro and Yukio were both in the interrogation room where a man with short brown hair sat with his hands handcuffed visible on the table.

The two were waiting for Mephisto to return with who he said could help with the case they were on. Shiro was getting odd vibes from what Mephisto said and who this mystery helper was. 

Shiro was pulled out of his thoughts on the subject as well as Yukio as the door opened and Mephisto reappeared with the mystery someone they were told about, his head down hair covering his eyes. Shiro had nostalgia from the length and colour of the boy's hair thinking of Rin at that moment before wiping the memory from his mind. 

"Is this who you were talking about Sir Pheles?" Shiro asked looking at the blue-net. "Of course, why else would I bring someone?" Mephisto asked one of his usual rhetorical questions. Shiro glared at the clown-like man. Mephisto only ignored and turned to the man across the table and walked over to lean on it. "Still not talking?" All he received was the silent treatment per usual from the man. "Fine," Mephisto smirked and Shiro's heart skipped a beat once he heard Mephisto call out the boys name and his head lifted up showing his azure blue eyes.

Rin walked over and sat down in the chair across the table and started for a moment before speaking up. "Want to talk?" Rin asked knowing the answer. Silence. With a blush looking away. Shiro noticed the odd behaviour of his long lost son. "Oh, c'mon I know you want to tell me~" Rin's seductive voice once again appeared and the man's face was becoming a lot like a tomato. The guy only continued to ignore the boy. Rin sighed, "we can take an answer to pound town if we must." Rin told him leaning forward and clasping his hands together. "I would lo- I would but I can't." The brown-haired male replied and Rin only smirked more. "Stop holding yourself back and tell me, please~" Rin pleaded and the man looked at him and instantly looked away. "I c-can't." His speech failed as he replied. 

Rin got up and went to the other side of the table the man simultaneously looked away from the hot figure standing beside him. Rin grabbed the man's chin forcing him to look at the half-demon. The man's face was cherry red now and only got redder - if that as possible that is. Mephisto smiled at his brother who he thought was rather naughty.

Mephisto walked over to the father and son in the room and stood beside them and spoke up. "So what are your thoughts?" Mephisto said in a jaunty manner. "You knew all along..." Shiro clenched his teeth trying not to lash out right then and there at the clown-like man. "Of course but I had no way of getting to him, father is rather possessive of things you know. He also dearly needed the training," Mephisto finished his explanation in his trademark devilish voice. "We're going to talk about this later," Shiro replied and Mephisto only scoffed and returning his attention to the scene in front of him.

The man was on the verge of responding but needed a little... Push if you will. Rin took his hand off the table and sat on the man's lap and whispered in the man's ear in his trademark seductive voice and the man cracked. "Wanna tell me now?" Rin asked and the man yelled out in frustration. "Fine! Whatever!" Rin leaned back with a proud expression. "The key is under the mat and the pin is 0298." The man finished and Rin looked back at Mephisto skipping past Shiro and Yukio, Mephisto nodded and Rin got off the man's lap and walked away from the blushing mess of a man. Rin was glad that it had ended quickly or they'd both be on the floor as a blushing mess. 

Soon as Rin got the answer he let his effect end. He stood before the three others in the room.

 _'Son... You seem so... Different.'_ Was Shiro's only thought that wasn't a question. "Thank you, darling," Mephisto thanked and Rin had a light blush on his cheeks and Mephisto grinned at the reaction he got of the younger. "Nah, it was nothing," "No need to be modest now," Mephisto's grin growing bigger and Rin frowned.

"Rin..." Rin's attention was brought to his name said by his younger brother. "Hm?" Rin tilted his head at his name. Rin was unsure how to act he didn't want to give all his affection and freak them out so he did the exact opposite and gave nothing. "Is it really you Nii~san?" Yukio asked as his eyes glossed over. "Of course it is, who else would it be?" Rin asked dumbly. "You're so different..." Shiro trailed off. "What happened to you Rin?" Rin stared at him confused. "What are you talking about?" The blue-net asked voices clueless. Rin had been feeling it all day but now it was becoming worse and more prominent. He looked at Mephisto and tugged his jacket and Mephisto got the message. Rin needed special "treatment". 


	4. Special 'treatment'

**Summary for the Chapter:**

> Rin's getting rather desperate for the special 'treatment' and Mephisto is determined to give to him. Shiro is determined to know what happened to Rin and sees something he's not supposed to in the process. 
> 
> Mephisto's also had a little surprise for Rin and it's finally revealed.

"Well, me and Rin must be off!" Mephisto announced as he grabbed Rin's hand which Rin gladly lets him do really needing to get out of the room. "Oh no you don't, you're going to explain everything here and now," Shiro stepped in front of two stopping them from leaving. Rin looked up at Mephisto worriedly and desperately. "Shiro." The older man said sternly not putting up with Shiro. "Mephisto, you're not taking my son anywhere who knows what you'll do to him!" Shiro spat his words angrily at the demon.

Rin was getting desperate he would do it right then and there if he had to but would rather not have seen his father and brother for the first time in nine years. Rin and Mephisto both noticed a tent starting to show in his pants. 

Mephsito sighed rather unhappy and desperate Shiro found it odd for the demon to show such emotion. "Please Shiro, I'm asking you this-" Mephisto was cut off by a muffled moan escaping Rin's mouth.

Shiro looked around seeing Yukio just as surprised as he was and Mephisto looking at Rin leading to the other two males to look at him as well. Rin stood with his eyes clenched, blushed cheeks and a large budge in his pants. "We're going." Before Shiro could protest the two puffed away in a cloud of pink smoke.

(Smut is written by me with a little help from AnimalsEML on Wattpad)

They puffed into Mephisto's luxury bedroom but Rin didn't notice not focusing on anything but his own desire for touch. "Big brother, please help me~" The younger moaned out eyes still clenched. The older demon smirked at the request. "Very well, as you wish little brother." He complied as he placed the younger on the bed.

The younger sat pushed up against the pillows after Mephisto poofed his teddy's into a pocket dimension. Mephisto got on the bed himself and started to kiss the teen. Said teen kissed back furiously unable to get enough of the older demon. 

Mephisto snapped his fingers letting both their clothes sit nicely folded in a pile off the bed. They separated and Rin looked at the Mephisto's body hungrily. 

Before Rin could stare any longer he was pulled into another kiss and let the older in without any question. The older pushed his tongue in exploring every crevice like a cave and the younger moaned at the feeling.

Mephisto pulled away only to trail butterfly kisses along his jawline then down his neck stopping to suck on his collar bone creating pink hickey that soon disappeared due to his demonic healing.

The young demon desperately wanted the older to skip the foreplay and move onto the main part but he knew nothing would make the older do so as he loved his play.

He moaned at the feeling of Mephisto's lips sucking on his body but he wanted so much more. The older knew this and decided to tease the boy. He trailed kisses down further to his v-line before going back up. The teen groaned unhappily, complaining. "Samuel... Why?" Sometimes he really hated the demon.

Mephisto reached a pink, hard nipple instantly sucking and playing with the other. Pre-cum continued to leak from Rin's member as he moaned at the treatment his nipples were receiving. 

Mephisto's hands were like electrifying as they roamed Rin's body sending waves of pleasure and couldn't help but moan at the impossible feeling. The demon really was something else.

The older soon swapped his activities on both nipples

The older demon brought his free hand down to the boy's leaking member and started to stroke it. The boy moaned loudly in response as his stomach coiled like a spring, his member ready to spill.

Mephisto sat up and Rin eyed the demon's member with lust and glee. "Go on," Rin didn't waste a second and leaned down and started to lick the demon's soft member but soon started to harden.

The older looked down with a small smile knowing what was to come.

The teen then took the member in bit by bit as he bobbed his head. Rin eyes stayed lidded with a blush painting his cheeks. Mephisto gave out a low moan at the treatment his now hardened member was receiving. 

Rin's eyes widened before closing after Mephisto's member hitting the back of his throat now deepthroating the older.

Said demon put his hand on Rin's head who looked up. "Good boy." His eyes shined in response as his face reddened further from Mephisto's unusual calm and kind voice. He didn't even notice the hand sneak behind him to stroke his tail. Rin moaned at the touch sensing vibrations and waves of pleasure down the older's member who moaned in response. 

His hand left the younger's head and began to pump his member. It wasn't long before he took his mouth from the member holding in a moan before letting it all out and strings of white sprang from the boy's member.

The older demon pushed the boy to the bed having already noticed the liquids leaking from his ass. In mating seasons the sub would create self-lubrication but for Rin and his kin, they could create it at the feeling of pleasure.

Mephisto poked a finger at Rin's puckered, slimy hole who groaned in displeasure. The younger didn't need to be prepared. He'd done it so many times he was used to the pain he didn't feel it anymore. Plus his demonic healing would heal him right up afterwards. 

Mephisto laughed at the boy's reaction before taking his finger away and aimed his member at his hole. He soon thrust in not wasting a second. He pulled right out and pushed back in fully and bent over whispering in the younger ears. "Get on your hands and knees for me." The younger obliged now in doggy style on the bed.

The demon continued to thrust in both feeling their stomachs coil. Rin's eyes widened as he gave out a loud pleasured moan as Mephisto hit his 'special' spot and proceeding to continue hit there on point. 

"I'm... Gonna cum~" Rin admitted, "me too~" The older second.

Both were distracted they didn't hear the noise of yelling or doors slamming and opening...

Rin moaned as he cummed and the door burst open as Shiro stood in shock looking at a flushed Rin cumming and Mephisto thrusting into Rin. Shiro didn't waste much time quickly closing the door letting himself be escorted out the mansion by Belial.

They both were shocked by the sudden intrusion but Mephisto continued to thrust before painting Rin's insides white. 

They flopped down on the bed after pulling out and breathed heavily, tired but satisfied. Rin felt great being filled again, he had missed the feeling dearly.

After they came down from their high Mephisto snapped his fingers and the bed was clean again. He pulled the covers over them as they cuddled and fell into a comfortable sleep. All snug and warm. And naked but not like either of them cared.

* * *

Rin awoke to find himself cuddling with Mephisto in his bed in the mansion. Rin looked around to see pink and purples decorating the walls, floor and bed. Teddy's and disturbing patterns also decorated the room.

"Morning darling." The younger looked up to see Mephisto smiling, the smile he only showed Rin. He couldn't help but give a small tired smile back with a weak 'morning'. 

Mephisto looked over to his bedside cabinet and pressed a button asking Belial to bring two breakfasts. The two of them sat up properly and Rin shivered at the cold air hitting his skin. 

Mephisto snapped his finger letting Rin now be loosely dressed in one of his red shirts. Rin smiled letting Mephisto's scent consume his own - more than it already had anyways.

Belial knocked before being told to enter and delivering two trays of food. Demons didn't necessarily need to eat but they both enjoyed the flavours.

They ate happily in bed discussing things before both had to get ready for the day ahead. Mephisto quickly freshened up himself with a snap of his fingers. The older now dressed leaving the younger naked and unclean. Mephisto smirked before poofing to his office before the younger could get angry at him.

Rin sighed smiling and shaking his head before going into the large bathroom with a large bath and shower. He turned on the shower enjoying the heat. He closed his eyes thinking about last night and couldn't help but feel pure ecstasy remembering Mephisto's electrifying touch. He could still feel the demon's hands roaming his body. 

The truth was Rin had fallen for the demon. He couldn't help falling for the demon who showed him so much kindness, he showed him parts he never showed to anyone else. When he was with the demon king he felt more comfortable than with anyone else. He made him truly happy.

But with unreturned love came a sickness. Hanahaki disease. He'd discovered this after puking up flowers and blood. He soon discovered what it was and was determined to hide it from everyone.

Rin cleared his mind and started to wash before drying and changing and taking a key to get to the office.

* * *

Rin entered to see Shiro complaining Mephisto about Amaimon being at True Cross. He froze remembering _that_ part of last nights activities.

They stared at each for a second not stopping their staring contest until Amaimon spoke up.

"Little brother?" "Amaimon!" Rin shouted instantly running and jumping up to wrap his arms and legs around the green-haired demon. Amaimon wrapped his arms around happy to see the other - or at least happy as he could be. But the smiles didn't last long.

Rin got off the older grabbing his collar. "I thought you left me behind or something! Where did you go?!" "Oh, big brother needed help with a surprise for you." Said boy looked over at Mephisto questioningly. 

The oldest had said something about a surprise while travelling and begged to know what it was but was never told. "Can you tell me what the surprise is now?!" Rin begged again. "He is the surprise," Mephisto admitted gesturing Amaimon. 

"Oh..." Rin looked down disappointed. "You bitch!" Amaimon said rather loudly pushing the older away. "Ahaha! I'm kidding!" Rin took a breath before continuing. "I'm glad you were the surprise." He smiled and Amaimon thought about it. "Fine." He opened his arms and they hugged again.

"What did I see last night?" Shiro interrupted. Rin signed knowing he'd have to talk about it sooner or later.

"Well-" "I'm demon king of Lust that's what happened," Rin told him coldly. "Now, this is a demon king only meeting so please leave," Rin ordered him not wanting to be in presence of his father any longer. Well, that's what he told himself anyway and Mephisto knew better.

They had only seen each other so many times but they knew each other very well. 

Rin tried pushing the older man out but he wasn't having any of it. He sighed and looked back at Amaimon then saw the windows.

Rin looked back at Amaimon grinning and he got the message. "No!" Mephisto yelled but it was the too late and the two of them had already run diving through the windows.

Mephisto gritted his teeth in annoyance and slid his hands down his fave groaning. He looked up to hear Shiro laughing.

"Kids am I right?" He asked grinding slightly.

Mephisto shook his head. "Kids my ass," Mephisto muttered glaring at the man then the window glaring, even more, realising he'll have to get Belial repair yet another window in which the demon had expressed distaste to.


End file.
